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Textile effluents are complex, making it difficult to choose an effective treatment. The textile effluent toxicity in Lactuca sativa after pulsed current (PC) electrocoagulation (EC) was evaluated in this study. The EC was performed using 304 stainless steel electrodes in batch mode. Parameters monitored included pH, temperature, color, and turbidity. Additionally, the process residue was subjected to energy-dispersive X-ray fluorescence (XFR) to determine the elements present. The process achieved proportional color and turbidity removal ranging from 97 to 99% and from 74 to 85%, respectively. Chemical oxygen demand (COD) and total nitrogen removal were 81 and 49%, respectively, in a 50 min time-lapse. The process generated approximately 1.7 kg of solid residue/m3 treated effluent. The XFR results revealed the presence, mainly, of Fe, Cr, and Ni ions in the residue, as well as chlorine. The germination index (GI) and relative growth values showed that EC reduced effluent toxicity slightly, indicating the need for complementary treatment.

Background: After more than half a century since the increase in the dumping of plastics in the oceans and other bodies of water, the damage caused by these products and their fractions has been verified. Its presence compromises the quality of the environment due to its prolonged permanence in the habitat and potential for the adsorption of substances and release of chemical compounds to the environment responsible for the durability of the plastic. Aims: This paper aims to gather information about the source, characterization, and interactions of micro- and nanoplastic in the environment and provide current material for those curious about this pollution. Methods: This review was conducted searching for papers on micro and nanoplastics on Science Direct, Springer, and Elsevier databases using keywords such as “microplastic”, “nanoplastic”, “sources”, “contamination”, “instruments”, “analysis,” and “ocean”. This review used only published works and comprise the last seven years of research on the topic from the date the review was initiated. The work is structured in the definition of micro and nanoplastics, main sources, levels of contamination, adsorption processes, and characterization techniques. Results: Degradation drives the main role in producing micro- and nanoplastic. Studies have reported interactions between microplastic and hydrophobic and hydrophilic compounds and demonstrated that microplastics can concentrate inorganic and organic compounds in several orders of magnitude, acting as vectors for co-pollutants in the environment. Discussion: Factors such as exposure time, pH, salinity, temperature, and adsorbate concentration directly affect MP-pollutant selection processes. The adsorption process might happen in presence of micro- and nanoplastic since organic pollutants have a high affinity with solid or particulate materials. Methodologies and quantification vary significantly among studies making it difficult to synthesize data. Conclusions: This study demonstrates that numerous techniques are being modified to characterize micro- and nanoparticles. However, standardizing analysis methodologies has proven challenging due to the nature of these particles and their nanometer-scale size.

In this work, we report the synthesis of magnetic zeolite A using fly ash as the main sources of SiO₂ and Al₂O₃, by hydrothermal use in the adsorption of Pb2, Cd2, Zn2⁺ and Cu2. The composite synthesis was successful, and the obtained material was characterised by using different techniques, such as X-ray diffraction (XRD), X-ray fluorescence (XRF), Infrared vibrational spectroscopy (FTIR), Electron Microscopy (SEM), and pH point of zero charge (pHpzc). XRD measurements confirm zeolites A as the main crystalline phases (98.5%), with the presence of a small amount of sodalite (1.5%). In the SEM of magnetic composite, the characteristic morphology for zeolite A was noted, with magnetite nanoparticles dispersed on its surface, resulting in a composite with magnetic properties. In the adsorption study, the magnetic composite showed a fast rate of adsorption, in which the pseudo second order model was the one that best described the experimental data of the metal ions under study. The Redlich-Peterson isotherm model best represented the experimental data of Pb2⁺ and Cd2⁺, while the Langmuir and Sips models fitted Zn2⁺ and Cu2⁺, respectively. Thus, the results showed that the magnetic composite presented high magnetic quality, facilitating its separation from the aqueous medium, as well as being a promising adsorbent in the adsorption of metal ions in aqueous medium.

A manipulação de materiais provenientes da indústria agrícola gera no decorrer da produção, grandes quantidades de resíduos orgânicos da agricultura e indústria, causando várias questões no ambiente resultante da concentração e descarte em áreas indevidas. A diversidade biológica da flora na floresta amazônica é de grande proporção, sendo eles os vegetais e seus respectivos frutos, podendo assim destacar-se a castanha-do-Pará que é retirada da planta com família lecythidaceae, com espécie bertholettia excelsa e seus frutos contendo sementes. A grande maioria da colheita brasileira de castanha-do-Pará é designada à utilização natural, entretanto quando são desaprovadas pelo mercado internacional por demonstrar-se danificadas ou fragmentadas, estas não são consumidas. O objetivo do presente trabalho foi caracterizar o ouriço da castanha-do-Pará através de técnicas analíticas, estrutural e de caracterização química, a fim de propor possíveis usos para esse material e seus subprodutos gerados na extração e no seu processamento agroindustrial. Para realizar a caracterização do resíduo da castanha-do-Pará foram utilizadas técnicas de infravermelho (IV) e Microscopia Eletrônica de Varredura (MEV). Os resultados da análise do IV apresentaram bandas que confirmam que o resíduo estudado possui em sua composição os principais constituintes da biomassa vegetal: celulose, hemicelulose e lignina, sendo considerado como resíduo lignocelulósico. As imagens obtidas na análise de MEV revelaram uma superfície fibrosa e irregular. Foram evidenciadas grandes perspectivas para a utilização do fruto, tanto em processos de adsorção utilizando o material como carvão ativado, carvão vegetal e biofertilizante.

Chemometric tools are powerful strategies to efficiently optimize many processes. These tools were employed to optimize a fast-solid phase microextraction procedure, which was used for the analysis of polycyclic aromatic hydrocarbons (PAHs) in oil-based produced water using a Headspace-Solid Phase Microextraction technique (HS-SPME/GC-MS). This optimization was achieved with a 24 factorial design approach, where the final conditions for this extraction procedure were 10 μg L-1, 1 h, 92 °C (at headspace), and 0.62 mol L-1 for PAHs concentration, fiber exposition to headspace, temperature, and NaCl concentration, respectively. The limit of detection (LOD) in this protocol ranged from 0.2 to 41.4 ng L-1, while recovery values from 67.65 to 113.10%. Besides that, relative standard deviation (RSD) were lower than 8.39% considering high molecular weight compounds. Moreover, the proposed methodology in this work does not require any previous treatment of the sample and allows to quantify a higher number of PAHs. Notably, naphthalene was the major PAHs compound quantified in all samples of the produced water at 99.99 μg L-1. Altogether, these results supported this methodology as a suitable analytical strategy for fast determination of PAHs in produced water from oil-based industry.

Literature is scarce on the performance of Fenton-based processes as post-treatment of municipal wastewater treated by upflow anaerobic sludge blanket (UASB) reactor. This study aims to perform Fenton and photo-Fenton from UASB influent and effluent matrices to remove micropollutants (MPs) models: atrazine (ATZ), rifampicin (RIF), and 17α-ethynylestradiol (EE2). A UASB reactor at bench-scale (14 L) was operated with these MPs, and the AOPs experiments at bench-scale were performed on a conventional photochemical reactor (1 L). A high-pressure vapor mercury lamp was used for photo-Fenton process (UVA-Vis) as a radiation source. Microcrustacean Daphnia magna (acute toxicity) and seeds of Lactuca sativa (phytotoxicity) were indicator organisms for toxicity monitoring. The UASB reactor showed stability removing 90% of the mean chemical oxygen demand, and removal efficiencies for ATZ, RIF, and EE2 were 16.5%, 45.9%, and 15.7%, respectively. A matrix effect was noted regarding the application of both Fenton and photo-Fenton in UASB influent and effluent to remove MPs and toxicity responses. The pesticide ATZ was the most recalcitrant compound, yet the processes carried out from UASB effluent achieved removal99.99%. The post-treatment of the UASB reactor by photo-Fenton removed acute toxicity in D. magna for all treatment times. However, only the photo-Fenton conducted for 90 min did not result in a phytotoxic effect in L. sativa.

The use of nanomaterials, described as structured materials of sizes between 1 and 100 nm, as adsorbents for specific application in the treatment of water and wastewater has been studied for the past few decades. This is mainly due to the adsorptive properties of these materials, such as, large surface areas due to their small size that promotes an increase in adsorption capacity and provides good catalytic activity. Another important property of nanomaterials is their mobility in aqueous media, making them potential adsorbents when applied to the removal of different classes of pollutants, such as: toxic metals ions, organic and inorganic compounds, and also bacteria

As águas residuais de plantas têxteis e fabricação de tinta têm despertado grande interesse na comunidade científica por serem os maiores consumidores de água e produtos químicos em seus processos. O uso contínuo de coagulantes químicos no tratamento dessas águas e efluentes têm causado impactos não só ao meio ambiente em geral como, também, à saúde pública que, diante desta problemática, tem-se estudado alternativas menos agressivas, como o emprego de coagulantes de origem vegetal ou mineral. A semente de Moringa oleífera, além de poder ser utilizada como coagulante no tratamento de águas, também exerce propriedades adsortivas no tratamento de coagulação-floculação de águas industriais, aumentando, assim, o poder de remoção de diversas classes de poluentes. A presente pesquisa teve como objetivo, avaliar o desempenho e viabilidade da aplicação da semente de Moringa oleífera como agente coagulador-floculador no tratamento de efluente de indústria de tintas. Para a realização dos experimentos, o efluente industrial foi coletado diretamente do reservatório da fábrica e utilizado sem pré-tratamento. Para otimizar as variáveis que atuam na eficiência do tratamento, foi utilizado como ferramenta o planejamento experimental. Foram variados três fatores: pH, massa do coagulante e velocidade de agitação da etapa de floculação. Para analisar a significância de cada efeito foram gerados os diagramas de Pareto. De acordo com o programa estatístico utilizado, as condições ótimas de operação, as quais minimizam os valores de cor e COT (Carbono Orgânico Total) foram: pH 3; agitação 3 e concentração de moringa 15 g/L. Já para os parâmetros condutividade e turbidez, as condições ótimas de operação, as quais minimizam os valores de cor e COT, foram: pH 9; agitação 7 e concentração de moringa 5 g/L. Entretanto, os fatores que foram estatisticamente significativos foram pH 9 para o parâmetro condutividade e o fator concentração do coagulante 15 g/L para o parâmetro turbidez. Em termos de eficiência de remoção, observou-se que para todos os experimentos, a eficiência de remoção de cor e turbidez ficou acima de 97%. Já a eficiência de remoção de COT nos diferentes testes variou de 32 a 46%. Foi possível concluir, que a semente de Moringa foi eficiente como agente clarificador de efluentes de alta complexidade, tornando-a uma alternativa sustentável e economicamente viável devido a facilidade de seu cultivo em regiões áridas e tropicais.

This work focuses on the validation and application of solid phase extraction followed by high-performance liquid chromatography (SPE-HPLC) analysis of important endocrine disruptors compounds (EDC) from different classes in highly complex wastewater matrix. The endocrine disruptors investigated included three different categories: pharmaceuticals (sulfamethoxazole (SMZ), trimethoprim (TMP) and diclofenac (DCF)), hormones (estrone (E1), 17α-ethinylestradiol (EE2) and 17β-estradiol (E2)) and plastic materials (bisphenol A (BPA)). The method involves pre-concentration by SPE using Strata-X extraction cartridges followed by HPLC coupled with diode array detector (DAD). As the assumption of homoscedasticity was met for analytical data, ordinary linear regression procedure was applied to the data. The method was considered validated for 7 EDC after consistent evaluation of the key analytical parameters. Recoveries were ranged from 52.3 to 179.6%. Limits of quantification were in the range 6.0-0.4 µg L−1. The described method was applied to evaluate the occurrence and removal efficiency of EDC in two biological sewage treatment plants (STPs). The influent mean concentrations of E1, E2 and EE2 hormones were 79.54; 175.09 and 102.19 µg L−1, respectively, while for SMZ, TMP, DCF and BPA were 215.17; 187.01; 218.97 and 87.12 µg L−1 for STP A, respectively. The efficiencies for the removal of EDCs ranged from 0 to 79.4%.

Emerging contaminants such as pharmaceutical residue brings harmful effects to the environment and human health as well. In Brazil, wastewater treatment plants (WWTPs) for influents and effluents do not remove efficiently that kind of residue due to the conventional biological-like treatment. In this context, alternative treatments, such as electrocoagulation can be used to achieve better removal efficiency based on electrolytic treatment. In this work, electrocoagulation processes (ECOF) were applied to remove antibiotics, such as trimethoprim (TMP) and amoxicillin (AMX) using a direct pulsed current (DPC). The electrocoagulation process was conducted using different anodes (304 and 316L steel electrodes and 1050 aluminum electrodes), and were evaluated experimental parameters such as corrosion rate, pH of the working solution and operational costs. In comparison with other electrodes, the 1050 aluminum electrode showed the larger corrosion rate, longer service life and smaller operational costs (energy and electrode consumptions). In addition, using of the pulsed direct current reduced the consumption energy of the electrocoagulation process by 30% when compared to the same process using direct current. During electrocoagulation process, the electrodes showed a complex hydrolysis equilibrium due to charge density transfer of the electrodes themselves which resulted in an acid-base equilibrium between hydrolysis products and AMX/TMP molecules. For 1050 aluminum electrodes, the pH of the electrolyte during electrocoagulation process changed from 3.0 to 5.5, and the cationic equilibrium containing Al3+ and Al(OH)2+ along the studied molecules was proposed. The same equilibrium approach was used in iron present in the steel electrodes: once the pH ranged from 3.0 to 7.0, the proposed equilibrium for this system evolves Fe3+, Fe(OH)2 and Fe(OH)3 compounds. To investigate the reactivity between AMX/TMP molecules and the electrodic surfaces, DFT calculations were conducted, and the analysis of molecular parameters in the experimental processes showed a passivation effect of AMX and TMP molecules towards 1050 aluminum electrode while AMX presented a corrosion effect in steel electrodes. Therefore, the 1050 aluminum electrode presented the best efficiency over steel electrodes in electrocoagulation process for AMX and TMP removal in wastewater, having potential to be applied in large scale application in a WWTP.

A numerical and experimental study of the multielement adsorption of Cd2+, Cu2+, Ni2+, and Pb2+ metal ions in batch and column system were carried out in aqueous solution using Tururi fibers as adsorbent. The kinetics and thermodynamic equilibrium parameters were studied. The adsorption kinetics was fitted to the homogeneous diffusion model and the results showed good linear correlation coefficients. Furthermore, a mathematical model was built to describe the mass transfer kinetics for fixed bed column tests. The effects of constant adsorption equilibrium, external mass transfer, and intraparticle diffusion resistance on breakthrough curves were studied. The equations which describe the phenomenology were discretized using the finite volumes method with the weight upstream differencing scheme and central difference scheme formulations. The results for the breakthrough curves obtained through simulation showed good agreement compared with the experimental data.

Montmorillonite (Mt) clay was pillared with SnO2 and tested as an adsorbent for the removal pharmaceuticals trimethoprim (TMP) and sulfamethoxazole (SMX) frequently present in wastewaters. Adsorption process was carried out in dynamic conditions and the effects of light exposure were investigated. The initial and modified clays were characterized using XRD, FTIR, SEM, potentiometric titration, TA/MS and adsorption of nitrogen. The XRD analysis revealed an enlargement of the clay’s interlayer space as a consequence of SnO2 particles intercalation into the clay interlayer spaces. A marked increase in the volume of mesopores was also noticed. It indicated the precipitation of tin species on the flake surface. These changes resulted in a five-fold increase in TMP adsorption. Upon exposure to light a 30% increase in TMP adsorption was found in comparison to the performance in the dark. The good performance of the modified clay was linked to specific acid–base and electrostatic interactions of TMP with the Lewis acid sites of SnO2. Since exposure to solar light resulted in the decomposition of some TMP adsorbed on the surface, those smaller molecules formed were able to relocate to small pores of higher adsorption energy, which were initially inaccessible for TMP. SMX was not adsorbed on the surface of the modified clay owing mainly to its acidic character.

This paper evaluated the occurrence and removal efficiency of four estrogenic hormones in five biological wastewater treatment plants (WWTPs), located in the State of Ceará, Brazil. The five WWTPs comprised: two systems consisted of one facultative pond followed by two maturation ponds, one facultative pond, one activated sludge (AS) system followed by a chlorination step, and one upflow anaerobic sludge blanket (UASB) reactor followed by a chlorination step. Estrogen occurrence showed a wide variation among the analyzed influent and effluent samples. Estrone (E1) showed the highest occurrence in the influent (76%), whereas both 17β-estradiol (E2) and 17α-ethynylestradiol (EE2) presented a 52% occurrence, and the compound 17β-estradiol 17-acetate (E2-17A), a 32% one. The occurrence in the effluent samples was 48% for E1, 28% for E2, 12% for E2-17A, and 40% for EE2. The highest concentrations of E1 and EE2 hormones in the influent were 3050 and 3180 ng L(-1), respectively, whereas E2 and E2-17A had maximum concentrations of 776 and 2300 ng L(-1), respectively. The lowest efficiencies for the removal of estrogenic hormones were found in WWTP consisted of waste stabilization ponds, ranging from 54 to 79.9%. The high-rate systems (AS and UASB), which have chlorination as post-treatment, presented removal efficiencies of approximately 95%.

Metal-impregnated carbons (Cu--AC; Ag--AC and Pd--AC) were studied as adsorbents for the desulphurization of liquid fuels. A real gasoline was examined for sulphur compounds. Textural characteristics of adsorbents were determined by nitrogen adsorption/desorption isotherms at 77 K. The adsorption isotherms were obtained by frontal analysis in a single fixed bed at 30 degrees C and 45 degrees C. Breakthrough curves were simulated according to a mathematical model that assumed axially dispersed flow and mass transfer described by a linear driving force approximation and nonlinear adsorption equilibrium reached instantaneously on the external surface of the adsorbents particles. The model was solved numerically by orthogonal collocation in finite elements, using the commercial solver gPROMS. The proposed model matched experimental data reasonably well. Resistance to mass transfer was significant and thought to be due to intraparticle diffusion kinetics. The results confirmed the efficiency of the use of activated carbon (AC) in the adsorption of sulphur compounds, especially when its surface is modified with metals. Comparing adsorption capacities of sulphur compounds from real gasoline, AC-Pd material appeared more selective than other materials, even presenting a behaviour of rapid saturation explained by the presence of other components competing for adsorption sites, reducing their effectiveness in removing sulphur compounds. Both pristine AC and Pd--AC showed good regenerability. The regenerated Pd--AC sorbent can recover about 85% of the desulphurization capacity.

Endocrine disrupting determination at low concentration levels comprises one of the most important targets in environmental analytical chemistry. In spite of inherent high sensitivities obtained for HPLC, these techniques have some limitations depending on the contaminants. As a result, interest in preconcentration using solid–phase extraction (SPE) still continues increasingly for endocrine disrupting determinations by HPLC due to the high accuracy of this method. In this work, we evaluated three different adsorbents in preconcentration of endocrine disruptors in three different categories: pharmaceuticals (sulphamethoxazole, trimethoprim and diclofenac), hormones (estrone, 17β-estradiolacetate and 17β-estradiol) and plastic materials (bisphenol A) in multicomponent aqueous solution using the combination SPE -HPLC. The adsorbents investigated were such as modified silica (octadecylsilane)—DSC-18 (Supelco) and two polymers, a divinylbenzene-N-vinilpirolidona—Oasis® HLB (Waters) and a styrene-divin...

The adsorption of aqueous solutions of BTEX (benzene, B; toluene, T; ethyl benzene, E; and xylenes, X) on hydrophobically modified zeolite was investigated. Multicomponent kinetics and equilibrium ...

The Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method was applied to the extraction of 14 organochlorine pesticides (OCPs) residues from commercial fruit pulps available in supermarkets in Fortaleza, Northeastern Brazil. The analyses were carried out by gas chromatography (GC), coupled to an electron-capture detector (ECD), and were confirmed by GC-tandem mass spectrometry (MS). The parameters of the analytical method, such as accuracy, precision, linear range, limits of detection and quantification, were determined for each pesticide. The results showed good linearity (R2 ≥ 0.9916) and the overall average recoveries were considered satisfactory obtaining values between 69 and 110%, RSD of 2-15 %, except for hexachlorobenzene (HCB) in acai, acerola and guava pulp samples. The OCPs were detected in guava (α-HCH; lindane) and soursop (α, β-HCH isomers) samples. The QuEChERS method and GC-ECD were successfully used to analyze OCPs in commercially available Brazilian fruit pulps and can be applied in routine analytical laboratories.

Buriti fibers were subjected to an alkaline pre-treatment and tested as an adsorbent to investigate the adsorption of copper, cadmium, lead and nickel in mono- and multi-element aqueous solutions, the results showed an increase in the adsorption capacity compared to the unmodified Buriti fiber. The effects of pH, adsorbent mass, agitation rate and initial metal ions concentration on the efficiency of the adsorption process were studied using a fractional 24−1 factorial design, and the results showed that all four parameters influenced metal adsorption differently. Fourier transform infrared spectrometry and X-ray fluorescence analysis were used to identify the groups that participated in the adsorption process and suggest its mechanisms and they indicated the probable mechanisms involved in the adsorption process are mainly ion exchange. Kinetic and thermodynamic equilibrium parameters were determined. The adsorption kinetics were adjusted to the homogeneous diffusion model. The adsorption equilibrium was reached in 30 min for Cu2+ and Pb2+, 20 min for Ni2+ and instantaneously for Cd2+. The results showed a significant difference was found in the competitiveness for the adsorption sites. A mathematical model was used to simulate the breakthrough curves in multi-element column adsorption considering the influences of external mass transfer and intraparticle diffusion resistance.

Various technologies have been used for the treatment and remediation of areas contaminated by BTEX (benzene, toluene, ethylbenzene and xylenes), which are organic compounds that are of particular concern due to their toxicity. Potential applications of synthetic zeolites for environmental fieldwork have also been reported worldwide. In this work, a hexadecyltrimethyl ammonium (HDTMA) surfactant-modified synthetic zeolite was investigated for its efficiency in removing BTEX from aqueous solutions. Three surfactant-modified zeolites were synthesized, with amounts of surfactant corresponding to 50%, 100%, and 200% of the total cation-exchange capacity (CEC) of the synthetic zeolite Y. The results of the BTEX adsorption experiments onto both synthetic zeolite and surfactant-modified zeolites (SMZ) showed that the SMZ-100 (zeolite modified with surfactant levels at 100% of CEC) was the most efficient modified zeolite for BTEX removal. Kinetics studies indicated that the multicomponent adsorption equilibrium was reached within 6 h and followed pseudo-second-order kinetics. The Langmuir, Freundlich, Redlich–Peterson and Temkin models were used to evaluate the BTEX adsorption capacity by SMZ-100. The Temkin model was found to be suitable for all BTEX compounds in a multicomponent system. Regeneration cycles of the modified zeolite were also performed, and the results showed that the adsorbent could be used efficiently in as many as four adsorption cycles, except for benzene.

Made available in DSpace on 2013-08-12T17:52:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-01-01 Made available in DSpace on 2013-09-30T19:12:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-01-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:30:38Z No. of bitstreams: 0 Made available in DSpace on 2014-05-20T15:30:38Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-01-01 A continuous flow reactor, inoculated with Aspergillus niger AN400, with total volume of 5 L was operated at 29 degrees C, with eight hours of retention hydraulic time and 150 L.h(-1) of air flow rate in order to remove 25 mg.L(-1) of Congo Red dye from a synthetic wastewater. The feeding of the reactor, inoculated with Aspergillus niger AN400, was done in two phases: Phase I, with 0,5 g/L of saccharose and Phase II, with no saccharose. In Phase I, it was possible to verify efficiencies of organic matter and color (mg Pt.L(-1)) removal of 80 +/- 16% and 82 +/- 10%, respectively. In Phase II, the efficiency of organic matter removal was 75 +/- 13% and color removal was 89 +/- 7%. The higher removals of nutrients were achieved by the reactor in Phase I with 25% to ammonia, 90% to nitrite, 93% to nitrate and 21% to phosphorus. Apparently, the presence of saccharose improved the removal of the nutrients. Univ Estadual Maranhao, Sao Luis, MA, Brazil Univ São Paulo, EESC, BR-05508 São Paulo, Brazil Universidade Federal do Ceará (UFC), Curso Saneamento Ambiental, Fortaleza, Ceara, Brazil IFCE, Curso Engn Ambiental, Fortaleza, Ceara, Brazil Univ Estadual Paulista Julio de Mesquita Filho As, São Paulo, Brazil Universidade Federal de São Carlos (UFSCar) Sorocaba, Curso Biol, São Carlos, SP, Brazil Univ Estadual Paulista Julio de Mesquita Filho As, São Paulo, Brazil

This review discussed the last 10 years progress in the use of lignocellulosic materials chemically modified as low-cost biosorbents. Thus, the chemical modifications, such as chemical pretreatment, oxidation, as well as the grafting of carboxyl groups, amines, amides, etc., on lignocellulosic fibers, that aim to increase the number of adsorption sites and maximize toxic metal ion adsorption capacity have been addressed. The literature presents results that indicated performances of biosorbents equal to or even higher than conventional methods and adsorbents. Many efforts have been concentrated on the improvements of these biosorbents through chemical modifications. However, some difficulties still exist, including the discharge of colored organic compounds resulting from the pretreatments and the development of fast, clean, and low-cost synthesis of selective and multifunctional adsorbents. Thus, the challenge for future research is to find solutions to these difficulties in order to finally make lignocellulosics biosorbents that can replace conventional adsorbent materials. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43286.

RESUMO – This work investigates the ability of modified stalk of Ricinus communis L., an agricultural biomaterial, to remove Cu ions from aqueous solution in a batch and fixed-bed column. Batch biosorption experiments indicated that the aximum adsorption capacity calculated by Langmuir model (qmax) was 131.04 mg/g for for MMB. Three significant variables (bed height, flow and initial concentration) were selected for further optimization via response surface methodology (RSM) based on Box–Behnken model. A statistically quadratic model was constructed on basis of which the threedimensional response surfaces were plotted.

The present study aimed at verifying the acid surface modification of dry bean pods subjected to alkaline pretreatment using tannic acid, poly(acrylic acid), and poly(acrylamide-co-acrylic acid) and evaluate their performances as adsorbents in the metal ions removal. Factorial design was used as a tool to study the variables that affects the modification processes. The results showed that there was an increase in the adsorption capacity after acidic changes, mainly for the tannic acid, achieving 45% increasing of removal of all metal ions. The variable pH had negative significant effect in the modification with tannic acid. When the modifying agent was the poly(acrylic acid), the variable initial concentration presented a positive significant effect. That means more poly(acrylic acid) was immobilized in the surface of the bean pod, resulting in higher capacity of adsorption. Temperature was significant variable in the modification with poly(acrylamide-co-acrylic acid), resulting in a strongly negative effect. Analyses of material characterization showed that soluble lipid fraction was removed after the alkaline treatment. Although no morphological changes were observed, there was an improving in the availability of the adsorbents sites after chemical modification. Further, the material exhibited thermal stability up to about 300 °C. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 135, 45879.

Wood-based activated carbon and its sulfur-doped counterpart were used as adsorbents of endocrine disruptor chemicals (EDC) from aqueous solution. Adsorption process was carried out in dynamic conditions and Thomas model was used to predict the performance of the column. The results showed a good fitting of the theoretical curve to the experimental data. S-doped carbon exhibited a higher adsorption capacity of trimethoprim (TMP) and smaller of sulfamethoxazole (SMX) and diclofenac (DCF) in comparison with the carbon with no sulfur incorporated into the matrix. The surface features of the initial carbons and those exposed to EDC were evaluated in order to derive the adsorption mechanism and elucidate the role of surface features. An increase in the amount of TMP from a low concentration solution (10 mg/L) on sulfur-doped carbon was linked to acid-base interactions and the reactive adsorption/oxidation of TMP. A decrease in SMX and DCF after sulfur doping was explained by a considerable increase in surface hydrophobicity, which does not favor the retention of polar DCF and SMX molecules. When the adsorption was measured from a high concentration solution at equilibrium conditions at the dark or under solar light irradiation different trends in the adsorption capacities were found. This was linked to the photoactivity of carbons and the degradation of EDC in the pore system promoted by visible light followed by the adsorption of the products of surface reactions.

This work investigates the removal of Cd 21 ,C u 21 ,N i 21 , and Pb 21 ions from aqueous solutions using tururi fibers as an adsorbent under both batchwise and fixed-bed conditions. It was found that modification of the tururi fibers with sodium hydroxide increased the adsorption efficiencies of all metal ions studied. The fractional factorial design showed that pH, adsorbent mass, agita- tion rate, and initial metal concentration influenced each metal adsorption differently. The kinetics showed that multi-element adsorption equilibria were reached after 15 min following pseudo-second-order kinetics. The Langmuir, Freundlich, and Redlich- Peterson models were used to evaluate the adsorption capacities by tururi fibers. The Langmuir model was found to be suitable for all metal ions. Breakthrough curves revealed that saturation of the bed was reached in 160.0 mL with Cd 21 and Cu 21 , and 52.0 mL with Ni 21 and Pb 21 . The Thomas model was applied to the experimental data of breakthrough curves and represented the data well. V C 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40883.

This work investigates copper, nickel and zinc ion biosorption in single- and multi-component systems in a fixed-bed column using green coconut shells (CS). Approximately 85% of biosorbents are in a particle size ranging from 0.25 to 2 mm. Operational parameters selected include a flow rate of 200 mL min−1 and a bed height of 100 cm, which were selected for a shorter execution time and good adsorption capacity. Empty-bed contact time and Thomas models were applied, showing a good fit with the experimental data. The column adsorption capacity increased after the green CS powder was treated in a column with NaOH at a concentration of 0.1 mol L−1. The highest values of adsorption capacities founded were 0.69, 0.45 and 0.39 mmol L−1 for Cu(II), Ni(II) and Zn(II), respectively, using green CS treated inside a column with NaOH of 0.1 M. The pH and chemical oxygen demand were monitored in the treatment solution and indicated that the adjustment of these parameters is necessary before disposal of these solutions. A study of desorption using an acid solution was carried out for recovery of metal ions.

The capacity of a periodic mesoporous organosilica (PMO) to adsorb the aromatic compounds benzene, toluene, o-, and p-xylenes (BTX), which are usually present in produced waters, was investigated under both column and batch processes. The PMO was synthesized by condensation of 1,4 bis(triethoxisilyl)benzene (BTEB) under acidic conditions by using structure-directing agent (SDA) Pluronic P123 in the presence of KCl. Thermogravimetric analysis showed that the presence of the surfactant decreases the thermal stability of the PMO. The small-angle X-ray diffraction pattern, as well as the nitrogen adsorption/desorption isotherm measurements, revealed that the synthesized material has a crystalline structure, with hexagonally-ordered cylindrical mesopores. The adsorption kinetics study indicated an adsorption equilibrium time of 50 min and also showed that the data best fitted the pseudo-first order kinetic model. The intraparticle diffusion model was also tested and pointed to the occurrence of such process in all cases. Both Langmuir and Temkin models best represented the adsorption isotherms of toluene; Langmuir and Redlich–Peterson models best represented the data obtained for the other compounds. Adsorption capacity decreases in the order benzene > o-xylene > p-xylene > toluene. Satisfactory results were observed in the application of the synthesized PMO for the removal of BTX from aqueous solution.

A novel procedure was developed for the synthesis of a periodic mesoporous organosilica (PMO), which was used to remove polycyclic aromatic hydrocarbons (PAHs) from aqueous solutions. Adsorption equilibrium isotherms and adsorption kinetics experiments were carried out in solutions of PAHs (2–60 mg L −1 ), using the PMO as adsorbent. Adsorption models were used to predict the mechanisms involved. The adsorption kinetics data best fitted the pseudo-first-order kinetic model for naphthalene, and to the pseudo-second-order model for fluorene, fluoranthene, pyrene, and acenaphtene. The intraparticle model was also tested and pointed to the occurrence of such processes in all cases. The isotherm models which best represented the data obtained were the Freundlich model for fluoranthene, pyrene, and fluorene, the Temkin model for naphthalene, and the Redlich–Peterson model for acenaphtene. PAHs showed similar behavior regarding kinetics after 24 h of contact between adsorbent and PAHs. FTIR, XRD, BET, and SEM techniques were used for the characterization of the adsorbent material.

A 51-year-old man with asthmatic attacks due to Cannabis sativa seed inhalation was studied. Specific IgE against this seed was demonstrated by in vivo (skin and bronchial challenge tests) and in vitro methods (reverse enzyme immunoassay and histamine release from basophils), suggesting a Type I immunologic reaction.